Heretofore, a pressure sensitive label application device was provided with a label detector 4 in a manner to detect the rear end position of a label 3 at the point of time at which the front end of the label 3 comes into contact with an article adapted to have the label 3 adhered thereto in accordance with the size of the label 3 adhered temporarily and continuously to a web of releasable backing material. The label detector 4 detected the state of "non-presence" of label 3 between the labels 3 as shown in FIG. 8a when the front end of the label 3 had reached the position at which the front end of the label 3 came into contact with the article (not shown). The device started applying the label 3 to the article, when the application device detected the position in which the front end of the label came into contact with the article. In this manner, the label 3 was adhered to the article.
The device in conventional use, however, was unable to apply the label 3 to the exact position of the article when the label being forwardly conveyed changed in its kind and size. As a result, it was necessary to move the label detector 4 to an exact position. Namely, the detector 4 had to be moved to the position in which the detector 4 could detect the state of "non-presence" of the label, as shown in FIG. 8a, in the case wherein as shown in FIG. 8b, the label detector 5 was detecting the state of "presence" of the label 3 when the front end of the label 3 came into contact with the article.
In that case, it needed time and labor to move the detector 4 to the position in which the detector could detect the state of "non-presence" of the label 3. In addition, it was not always easy to move the detector 4 to such a position. Accordingly, when there was change in the kind and size of the label 3 in the conventional devices, movement of the label detector 4 was a very cumbersome operation that required time and labor. Moreover, correctness in application of the label to the exact position of the article was hardly expected from the conventional application devices.